Slack adjuster for brake mechanism



1927. Apnl w. s. ADAMS SLACK ADJUSTER FOR BRAKE MECHANISM 2 Sheets-Sheet 1 Filed July 5. 1925 April 19, 1927. 1,625,695

w. s. ADAMS S LACK ADJUSTER FOR BRAKE MECHANISM Filed July 3. 1925 2 Sheets-Sheet 2 Patented Apr. 19, 1927.

UNITED STATES 1,625,695 PATENT OFFICE.

WALTER S. ADAMS, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THE J; G. BRILL COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF IPENN SYLVANIA.

SLACK ADJUSTER FOR BRAKE MECHANISM.

Application filed July 3,

The present invention relates to a slack adjuster of the general type disclosed in Patent 1,407,628. to Berry and Applegate dated February 21, 1922. In the mechanism shown in the patent the actual movement to take up slack is effected by means of a spring, after the spring has been compressed by air pressure. This construction has certain. disadvantages among which is the fact that considerable space is required for a spring sulficiently powerful to cause the desired movement. One of the objects of the present invention is to provide the movement by the direct action of the air pressure, only a relatively small spring being necessary to return the parts to normal position when the air pressure is released. Other objects of the invention willbe apparent from the following specification and claims.

In the accompanying drawings, I have shown one embodiment of the invention, but it will be understood that the drawings are for illustrative purposes only and that various changes and substitutions may be made within the scope of the appended claims without departing from the spirit of the in vention. Particuarly it will be understood that the brake mechanism as shown is merely typical of the various types of brake mechanisms to which the invention is applicable.

Oi. the drawings:

Fig. 1 is a plan View showing a part of a railway truck with my improved slack adjuster incorporated therein.

Fig. 2 is a side view of the parts shown in liig. S is a transverse view partly in section along the line 3, of Fig. l. and showing the adjusting mechanism to which the invention particuarly relates.

Fig. 4 is a detailview showing in section the check valve which is used in conjunction with the adjusting cylinder.

Referring to the drawings, 1 is aside member and 2., 2 are transverse members of the frame of a railway truck. This frame is supported in any usual or preferred way on axles 5}, 3 carried by track wheels 4, l.

ilral-re shoes 5 are provided in position to engage the wheels 4-, l and it will be understood that similar shoes are provided to r engage the wheels (not shown) at the oppo- 1925. Serial No. 41,287.

are suspended from the frame by means of links 6, 6. F or forcing the brake shoes against the wheels there are provided two brake beams 7, 7. These beams extend trai'isvorsely of the truck and are connected at their ends with the brake shoes at the two sides of the truck.

these levers being connected between their respective ends at 10 and 11 with compression members 12 and 13. These members 12 and 13 are suspended from the frame by means of links 14 and 15 and at their opposite or outer ends they engage the respective brake beams 7, 7 The shorter arms of the levers 8 and 9 are connected together by means of a. compression link 16 which is pivotally connected with the two levers at 17 and 18 respectively. Pneumatic means is provided for separating the two longer arms of the lovers 8 and 9. This means comprises a main cylinder 19 with the usual piston therein, the cylinder and piston being connected with the respective levers at 20 and 21. The cylinder is supported on the truck frame by means of bars or beams 19, 19*. The cylinder 19, together with the various operating and controlling parts therefor, constitutes no part of my present invention and these various parts are thercfore not shown in detail.

From the foregoing description, it will be clear that when the levers 8 and 9 are actuated by the air cylinder mechanism, the two pivot points 20 and 21 are separated thus moving the two members 12 and 13 relatively in opposite directions and also moving the break beams 7 7 in opposite directions so as to force the shoes 5. against the wheels 4, l. Springs 22, 22 are provided. for assisting in the withdrawing of the brake shoes from the wheels when the pressure released from the levers 8 and 9.

Preferably one of the levers, as for instance 9, is extended and is pivotally connected at 2" with a link 24 wherebythe brake mehanism can be operated iudepcnd ently of the cylinder mechanism 19,

In order to adjust the mechanism so that the shoes may be engaged with the whee s upon a predetermined movement of the cylinder mechanism the link 16 is adjustable in length, comprising two parts 16 and 16 which are connected by means of a right- For moving the brake beams 7, '7 two levers S and 9 are provided,

and-left-hand threaded connecting device or turnbuckle 16. turning the device 16, the two parts 16 and 16 will be forced apart thus increasing the etlective length of the link and moving the shoes 5, 5 closerto the respective wheels at, l.

As shown more clearly in Fig. 3, I provide a ratchet wheel 25 which surrounds the connecting device 16. Provision is made whereby the connecting device may slide longitudinally through the ratchet wheel although rotatably connected therewith. As illustrated the central part of the connecting device is hexagonal in shape and the hole through the ratchet device is similar in shape. Journaled on the hub of the ratchet wheel is a casing 26 which extends horizontally and is provided with a cylindrical chamber 27. Secured to the casing 26 is a cylinder 28 which is closed at the end opposite to the casing. The casing and cylinder are supported by a link 28. Slidably mounted on the cylinder 28 is a piston 29 which is provided with a packing 30 or with other suitable means for preventing the leakage of air between the piston and the cylinder walls. Pivot-ally connected with the piston 29 is a connecting rod 31 which terminates in a pawl 32 in position to engage the teeth of the ratchet wheel 25. Thus when air is admitted to the cylinder the ratchet wheel is turned in the counterclockwise direction. A coil spring 33 located partly in the chamber 27 and partly in the cylinder 28 engages the piston 29 and tends to hold it in its right hand or outermost position.

Preferably the casing 26 entirely encloses the ratchet wheel 25 and also the connecting rod 31 and the pawl 32 so as to protect these parts from injury and also to retain oil or grease and exclude dirt. A short link 34 is preferably connected with the pawl 32 and extends through a small opening in the upper wall of the casing 26. This opening is of suiiicient size to permit the free movement of the link to accommodate the movements of the pawl. The link serves as a means for manually disengaging the pawl from the ratchet wheel when it becomes necessary to turn the connecting device 16' in the direction opposite to that in which it is turned by the ratchet wheel.

Connected with the main air cylinder 19 is a pipe 35, this pipe being connected to the cylinder at such a position that air is admitted to it whenever the piston in the cylinder moves beyond a certain predetermined position. The pipe is flexible and extends to the cylinder 28 and serves to admit air to this cylinder through an opening 36. The air thus admitted tends to move the piston 29 towards the left and when the cylinder is thus moved the ratchet wheel 25 and the connecting device 16 are rotated in the counterclockwise direction. In this way the It will be observed that, by

effective length of the link 16 is increased. The spring 33 is compressed as the piston moves and tends to return the piston to its original position as soon as the air pressure is released. The cylinder 28 is pro vided with one or more ports 37, 37 which are opened when the piston 29 reaches the end of its stroke. These ports serve to permit the escape of air from the cylinde' and the piston is then returned to its original posit-ion by means of the spring 33. The casing 26 is provided with a shoulder 26 which serves as a positive stop for limiting the movement of the piston. Ordinarily. however, the piston does not engage this stop as the air is first exhausted through the ports 37, 37.

Preferably a check valve 38 is provided in the pipe 35. This check valve is shown in detail in Fig. 4: and it comprises a moveble valve element 39 which is normally held open by gravity. The valve is preferably arranged at an angle, as shown, so as to permit it to be easily closed when the pressure in the cylinder 28 exceeds that in the cylinder 19. This check valve, therefore. serves to prevent the air from flowing backward from the auxiliary cylinder into the main cylinder.

As already stated, the pipe 35 is connected with the main cylinder at a position which corresponds to the desired maximum travel of the piston in the said cylin der. The brake shoes are subject to rapid wear and as these shoes wear a longer travel of the piston is necessary in order to set the shoes against the wheels. Whenever this tavel of the piston extends beyond a predetermined position, air is admitted to the pipe 35 and through this pipe to the cylinder 28. At this time, however, the link 16 is under heavy compression and the air pressure in the cylinder 28 is not sullicient to rotate the connecting device 16". Thus pressure is maintained in the cylinder 28 so long as the brakes are applied but the piston 29 remains stationary. As soon as the brake shoes are released by the cylinder mechanism 19, the compression in the link 16 is released and the air under pressure in the cylinder 28 serves to immediately rotate the ratchet wheel and the connecting device. This increases the effective length of the link 16 and moves the shoes 5 closer to the respective wheels. The check valve 38 serves to preventthe air in the cylinder 28 from escaping hack into the main cylinder 19.

As soon as the ports 37, 37 are uncovered. the pressure in the cylinder 28 is released and the check valve immediately opens. Thereupon the spring 33 returns the piston and the attached parts to their normal positions and the small amount of air ontrapped in the cylinder 28 flows through the open check valve, this air not being sufficient in amount or in pressure to close the said check valve.

From the foregoing description, it will be clear that my improved mechanism serves automatically to adjust the brake mechanism to compensate for the wear of the brake shoes thus causing the travel of the main piston to remain substantially uniform. The adjustment is effected directly by the air pressure and not by a spring. It will be understood that the operation, which has been described, does not take place at each application oi the brakes but only at intervals in accordance with the amount of wear.

W hat I claim is:

1. An automatic slack adjuster for brake mechanism comprising in combination, brake shoes, actuating mechanism for the brake shoes including an adjustable element, an auxiliary cylinder mechanism, means for admitting air to the cylinder whenever the actuating mechanism moves beyond a predetermined position, means connected with the cylinder mechanism for adjusting the adjustable element when the cylinder mechanism is operated by the direct action of the air admitted as aforesaid, and means for retaining air in the cylinder mechanism to permit delayed action after the brake shoes are released by the actuating mechanism.

2. In a slack adjuster for a railway car brake mechanism, the combination with car wheels, of brake shoes adapted to engage the respective wheels, operating mechanism for the brake shoes including an adjustable element, a main air cylinder with a piston therein for actuating the operating mechanism, an auxiliary air cylinder with a piston therein, air connections for admitting air to the auxiliary cylinder whenever the piston in the main cylinder passes a predetermined position, means connected with the piston in the auxiliary cylinder for adjusting the said adjustable element when the said piston moves under the direct action of the air admitted as aforesaid, and means for retaining air in the auxiliary cylind-er to permit delayed action of the piston after the brake mechanism is released by the piston in the main cylinder.

3. In a slack adjuster for a railway car brake mechanism, the combination with car wheels, of brake shoes adapted to en gage the respective wheels, operating mechanism for the brake shoes including an adjustable element, a main air cylinder with a piston therein for actuating the operating mechanism, an auxiliary air cylinder with a piston therein, the last said cylinder having an exhaust port adapted to be uncovered by the piston when the latter reaches a predetermined position, air connections for admitting air to the auxiliary cylinder whenever the piston in the main cylinder passes a predetermined position, and means connected with the piston in the auxiliary cylinder for adjusting the said adjustable element when the said piston moves under the direct action of the air admitted as aforesaid.

4. In a slack adjuster for a railway car brake mechanism, the combination with car wheels, of brake shoes adapted to engage the respective wheels, operating mechanism for the brake shoes including an adjustable element, a main air cylinder with a piston therein for actuating the operating); mechanism, an auxiliary air cylinder with a piston therein, air connections for admitting air to the auxiliary cylinder whenever the piston in the main cylinder passes a predetermined position, a check valve for retaining air in the auxiliary cylinder to permit delayed action of the piston after the brake mechanism is released by the piston in the main cylinder, the said check valve being normally open so as to permit the return passage of a small amount of air, means connected with the piston in the auxiliary cylinder for adjusting the said adjustable element when the said piston moves under the direct action of the air admitted as aforesaid, and a spring for returning the last said piston with the parts thereto attached to its initial position after movement thereof by the air.

5. In a slack adjuster for a railway ear brake mechanism, the combination with car wheels, of brake shoes adapted to engage the respective wheels, operating mechanism for the brake shoes including an adjustable element, a main air cylinder with a piston therein for actuating the operating mechanism, an auxiliary air cylinder with a piston therein, the last said cylinder having an exhaust port adapted to be uncovered by the piston when the latter reaches a predetermined position, air connections for admitting air to the auxiliary cylinder when ever the piston in the main cylinder passes a predetermined position, a check valve for retaining air in the auxiliary cylinder to permit delayed action of the piston after the brake mechanism is released by the piston in the main cylinder, the said check valve being normally open so as to permit the return passage of a small amount oi air, means connected with the piston in the auxiliary cylinder for adjusting the said adjustable element when the said piston moves under the direct action of the air admitted as aforesaid, and a spring for returning the last said piston with the parts thereto attached to its initial position after movement thereof by the air.

WALTER S. ADAMS. 

